The effect of three weeks ex vivo supplementation with 30 μM ebselen or 7.5 mM NAC on the intracellular GSH: GSSG ratio in human PBMCs or CD4+T cells isolated from fresh human blood derived from five different healthy donors aged 55–60 years. A &C denote the effect of antioxidants in human PBMCs and B &D denote the effect of antioxidants in CD4+ T cells. The bars indicate the mean ± S.D. Values statistically different from their controls (Student’s t-test, 95% confidence level) are indicated with an asterisk. **p < 0.01, ***p <0.001 – Significantly higher than the ratio of non-supplemented cells.